diff options
| -rw-r--r-- | block/blk-settings.c | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 78549c72378..605df9b3de8 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -212,26 +212,30 @@ EXPORT_SYMBOL(blk_queue_bounce_limit); /** * blk_queue_max_sectors - set max sectors for a request for this queue * @q: the request queue for the device - * @max_sectors: max sectors in the usual 512b unit + * @max_hw_sectors: max hardware sectors in the usual 512b unit * * Description: - * Enables a low level driver to set an upper limit on the size of - * received requests. + * Enables a low level driver to set a hard upper limit, + * max_hw_sectors, on the size of requests. max_hw_sectors is set by + * the device driver based upon the combined capabilities of I/O + * controller and storage device. + * + * max_sectors is a soft limit imposed by the block layer for + * filesystem type requests. This value can be overridden on a + * per-device basis in /sys/block/<device>/queue/max_sectors_kb. + * The soft limit can not exceed max_hw_sectors. **/ -void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors) +void blk_queue_max_sectors(struct request_queue *q, unsigned int max_hw_sectors) { - if ((max_sectors << 9) < PAGE_CACHE_SIZE) { - max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); + if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) { + max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9); printk(KERN_INFO "%s: set to minimum %d\n", - __func__, max_sectors); + __func__, max_hw_sectors); } - if (BLK_DEF_MAX_SECTORS > max_sectors) - q->limits.max_hw_sectors = q->limits.max_sectors = max_sectors; - else { - q->limits.max_sectors = BLK_DEF_MAX_SECTORS; - q->limits.max_hw_sectors = max_sectors; - } + q->limits.max_hw_sectors = max_hw_sectors; + q->limits.max_sectors = min_t(unsigned int, max_hw_sectors, + BLK_DEF_MAX_SECTORS); } EXPORT_SYMBOL(blk_queue_max_sectors); |